stress test with send-mode = round-trip
blocking-read event
got event #gnu.x11.event.Expose 12 #Window 29360129 256x256+10+10
try round-trip request
done round-trip request
blocking-read event
try round-trip request
done round-trip request
try round-trip request
done round-trip request
try round-trip request
done round-trip request
try round-trip request
done round-trip request
got event #gnu.x11.event.KeyPress 2 #Window 193010067 0x0+0+0